1. Field of the Invention
The present invention relates to a resin composition curable by an active energy-ray for use for forming a wall of an ink path of an ink jet head. The present invention also relates to an ink jet head having a wall of ink path formed by use of the resin composition, a process for preparing the head, and an ink jet apparatus provided with the head.
2. Related Background Art
Conventionally, ink jet heads for ink jet recording systems are produced by forming fine grooves on a substrate made of a metal, a metal oxide, or the like by fabrication means such as cutting, etching, and the like and subsequently bonding the substrate to another substrate to form a flow path.
Such a conventional process involves disadvantages that it cannot give a narrower flow path with high precision to satisfy sufficiently the requirement resulting from the recent increase of recording density, and that the alignment between the grooves for forming flow paths, and piezoelectric elements or electrothermal transducers for generating energy to be utilized for ejecting ink is difficult, resulting in low production yields. To solve such problems, Japanese Laid-Open Patent Application Nos. 61-154947, and 62-253457 disclose processes for producing ink jet heads. An example of processes for producing an ink jet head is briefly described by referring to figures.
Firstly, as shown in FIG. 1, a positive type dry film or the like is laminated on a base plate 1, and is subjected to patterning treatment to form a solid layer 2 on the position where the nozzles are to be formed.
Then, as shown in FIG. 2, a curable resin composition 3 is applied on the base plate 1 by potting.
Subsequently as shown in FIG. 3, another substrate 4 is contact-bonded, and the curable resin is cured.
Next, as shown in FIG. 4, the solid layer 2 only is dissolved off by using an aqueous alkali solution, thereby completing ink flow paths.
In such processes, the solid layer 2 is generally formed from a positive type photosensitive material because of ease of removal and simplicity of patterning. The curable resin composition 3 is prepared from an active energy-ray curable resin rather than from a thermosetting resin because of ease of forming various fine patterns in addition to the flow path pattern by merely using a mask.
The processes described above still have disadvantages that the flow path pattern cannot readily be formed with high precision and high density, so that further improvement is desired.
A disadvantage to be offset, for example, is that the solid layer 2 may come to be dissolved or swollen by the resin composition 3 laminated thereon because the solid layer 2 is made of a positive type photosensitive material which is a special material having relatively high solubility and swelling characteristics. Sometimes in a finished ink jet head, the conventional resin compound 3 exerts a strong interaction with a liquid ink, so that the problem remains of deformation of the flow path caused by swelling of the flow path forming material. Furthermore, the conventional resin composition 3 may have insufficient adhesion force for bonding to various surface to be bonded (e.g. SiO.sub.2, polyimide, glass, etc.), where exfoliation or separation of the resin composition may occur.